Pests in Gardens and Landscapes: Quick Tips
Weeds in Landscapes
Hoe or remove weeds with tools.
Nothing disturbs tidy gardeners more than a weed filled flower or landscape bed. Weeds will invade any bare or thin area in a landscape. Prevent invasions in new beds with good site preparation. Keep weeds out with an integrated program that includes competitive plants, mulches, and hand removal. Be particularly vigilant about removing aggressive perennial weeds. You rarely should need herbicides in established landscape plantings.
Before and right after you plant:
- Prepare the site and control existing weeds.
- Dig out weeds or remove by hand. Follow up by irrigating then removing newly emerged weed seedlings right before planting.
- Solarize the soil if conditions allow.
- If necessary, use glyphosate or other systemic herbicides for difficult-to-control perennial weeds.
- Evaluate your soil and amend if needed. Make sure new soil comes from a reputable source and doesn’t contain weed seeds.
- Establish new plantings as quickly as possible to cover bare areas and shade out weeds.
- Consider drip irrigation in permanent plantings.
- Apply mulches.
Mulch is the key to weed-free landscaping.
- Mulches prevent weed seed germination by blocking sunlight. Be sure to properly apply mulch and replenish it to maintain its effectiveness.
- Organic mulches (e.g., wood chips, bark chips, compost): Attractive but must be replenished. Choose a medium-sized mulch (3/4 inch) and maintain it at an adequate depth (3 to 4 inches).
- Natural inorganic mulches (e.g., sand, gravel, pebbles): More stable than organic mulches, but difficult to keep clean.
- Landscape fabrics: Porous and long lasting; vary in how long they remain effective. Cover with organic mulch.
- Black plastic: Not preferred since it can restrict air and water movement and promote root rots.
When weeds invade your landscape:
- Remove small weeds by hand before they flower and set seed.
- Use a dandelion knife or similar tool to dig up and destroy all roots and underground parts of perennial weeds without disturbing the soil.
- Use shallow cultivation or hoeing to remove annual weeds from ornamental plantings.
- Consider devices such as string trimmers for large landscapes.
- Apply mulch to weed-free areas to prevent further invasions, and regularly remove new weeds as soon as they emerge.
When are herbicides necessary?
- In general, existing landscape plantings don’t need herbicides; hand weeding and mulching usually provide adequate control.
- Use herbicides for special-problem situations before establishing new plantings or for difficult-to-control perennial weeds.
- Herbicides can injure desirable plants in the landscape, so use these products with great care.
Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.